With the availability of a practical extraterrestral payload delivery system, science and engineering research facilities have accelerated their efforts to design and construct large-scale orbital structures (e.g. a space station), where advantage can be taken of both weightlessness and absence of the electromagnetic absorbtion and reflection characteristics of the earth's atmosphere. Among the various types of assemblies to be deployed on such structures are large surface area electromagnetic energy (e.g. solar energy) directing mechanisms (e.g. focussing reflective or refractive assemblies).
A typical electromagnetic energy concentrator assembly incorporates a three-dimensional, compound-curved structure shaped to conform to a paraboloid of revolution. Because of its compound (e.g. double) curve configuration as well as its large size (e.g. 15 meter diameter, 5 meter depth), the construction, packaging (launch vehicle stowability) and successful deployment of such a structure is considered to be a costly and complex engineering exercise. On the one hand the manufacture of compound curved reflector or lens elements involves complex tooling components and consequential high fabrication costs. In addition, the interconnection of radial and cord members of the support framework typically requires tensioning of structural components in both radial and circumferential directions, thereby necessitating the use of stress members on both sides of the energy directing surface in order to obtain contour equilibrium.